Process for preventing mine explosions



Patented Sept. 20, 1927.

UNITED srarrss eater OFFICE.

WALTER EDWIN TRENT, OF WASHINGTOI T, DISTRICT OF COLUMBIA, ASS IGNOR TO TRENT PROCESS CORPORATION, OF NEW YORK, N. Y., A CORPORATION OF DELA- WARE.

PROCESS FOR PREVENTING MINE EXPLOSIONS No Drawing.

The invention relates to improvements in a method for preventing dust explosion in coal mines.

In the operation of mines at the present time it is the practiceto distribute inert dust such as powdered limestone, shale, silica, soil, or the like, on the roof ribs and floors of coal mine workings and all places wherever practicable that may offer lodgement for floating coal dustfe This causes dilution of the settled cosi dust and retards the exothermic reaction that concentrated coal dust sets up by oxygen entrainment in the dust and adjacent thereto and by thus retarding the initial heat reactions the coal is less liable to heat up to kindling and explosive temperature.

It is impossible to get a uniform distribution of the dust over the surfaces of the.

roof, ribs and floor, in the ordinary dusting operation as about two thirds of the dust will get to the floor and one third over the other surfaces and this ratio should be reversed.

An effort to get a more uniform distribution has led to a practiceof spreading. adobe mud over these surfaces, but mud, both in its wet condition and after drying and caking, will not permit the coal dust properly to mix with the same to get the desired dilution.

In the case of neither dust nor mud is the physical character of a coal dust particle changed so as to make it inert or prooi against exothermic reaction at ordinary mine working temperatures.

It is an ob 'ect of the invention to prevent coal dust explosions in mines by coating coal particles with a skin or covering of a high fiash point viscous oil that will permanently 40 prevent the particles from se'ttin up low temperature oxidation and then urtherto safeguard the particles fromcombustion conditions by imbedding them in a bed or surface of the heavy combustion resistant oil.

In my Patent Number 1,479,757, I have disclosed a process by means of which line coal is prevented from exploding and also from dusting. I disclose in this patent a process in which a small percentage of high 50 boiling point oil is mixed with coal dust in an amount sufficient to put a thin film or coat around each particle. This oil coating produces two effects, first itcompletely prevents the coal particle from generating heat 61: by slow low temperature oxidation or com- Application filed Octohcr 243, 1924. flex-in! No. 4,84%

bust-ion and prevents the coal particles from dustinggf that is, it causes it to stay settled under ordinary conditions.

In my Patent No. 1,420,165, I disclose the marked affinity between oil and coal dust and their characteristics to form a true amalgam. Both the filming of the coal par ticles with oil then embedding or amalga mating these particles in a layer of oil are factorsin preventing coal dust explosions.

The invention primaril consists in applymg to exposed wail sur aces of a mine, or to any surface that offers lodgement or col looting places for dust. a high boiling point oil which is high in flash point and serves to lodge or entrap particles of coal dust.

It is contemplated to direct; the travel of circulating air that has, or may have at tunes, suspended coal particles so as to give contact with the oil covered surfaces to hasten and localize the collection of the dust so far as it may prove practicable in names,

In addition to dusting and mudizing there has been put into practice a most highly eii'ective system described as dust barriers. This practice consists in. the principle of placing comparatively large amounts of inert dust at strategic points in mines, the containers being delicately positioned so that at any slight atmospheric disturbance the containers will spill the and permit same to become diffused in the air or gases and thus cause the retardation or sut foca i of flame propagation of an explosion at inciprency.

This system may be called a second line of defense and I wish to acknowledge its novelty and its great usefulness and fa ther to say that the present method descri does not lend itseif to this particular practice to prevent or retard an explosion already inaugurated and that it is a system that should be used with the present disclosure for a second line of defense as now used.

Referring non more specifically tome in-- mention I preferably coat the walls and faces of a mine with a hydrocarbon oil hav ing a very high flash point with sutficicnt viscosity to remain on a surface after hav ing been piaced thereon; I may use the residuai oil from an oil crackin access it can use aiso certain topped oils from which has been removed the gasoline and intermediate boiling point fractions. This oil an Hit plied by spraying, painting, or otherwise, in such places as coal particles are to be found.

The particles of coal suspended in the air contact with the hydrocarbon oil and because of the existing afiinit between coal At places where dust is collected in rather large uantities it'will be necessary to remove t e amalgam by scraping or otherwise and then applying t e new surfaces of oil.

I may place ventilating fans in the mines to direct the air currents carrying,- the coal dust so as to contact with the, oiled surfaces or I may direct those currents by an other means. The oil to be used is prefera ly one that contains only fractions that boil at about 300 centigrade and upwards. The ordinary fuel oils of about 12 or 14 Baum "i'avity from which have been removed all ?racti0ns that boil up to 300 centigrade are very. suitable. Heavy transformer oils are likewise suitable and also oils that have the flash point specificationsof lubricating oils. Greases of many kinds answer the purpose and cheap oil water emulsions such as base sediment are fit for the pur ose.

If it is desired to use a t in oil that has the other necessary characteristics it becomes suitable by thickening the same dry shale or rock dust so that it will remain on the surface after being applied. In fact any semi liquid material that does not harden and thatwill absorb and hold coal dust and has the desired adhesive characteristics of the oil may be utilized in accordance with this invention.

Having thus described my invention what I claim is:

1. A process for preventing mine ex 10- sions, consisting in ap lying-a hydrocar on oil having ahigh boiling point and a high flash point to a mine surface to entrap and retain finel divided'coal particles contacting therewith to render said particles sub stantially incapable of an exothermic reaction.

2. A process for reventing mine explosions which consists in applying a hydrocarbon oil having a high boiling int to a mine surface to entrap coal particiiz and to separate them so'as to prevent an exothermic reaction from occurring between said particles.

3. A process of collectingcoal dust carried in air suspension in a mine to render the same immune to low temperature reac tion with oxygen,-consistinq in applying to the surface of the mine a high boiling point oil and in bringing the dust particles in contact with said oil surface to coke and agglomerate said dust particles.

In testimony whereof I afiix my signature.

WALTER EDWIN TRENT. 

